Tray forwarding mechanism

ABSTRACT

A mechanism for pushing forward filled trays such as pulp or plastic trays comprising a shoe means having a slanted face inclined to flushly engage the tray sidewall, and slightly lift the same while forwarding such that the sidewall is lifted into pressure engagement against the underside of a stop means or stop block disposed above the shoe means. The stop block and shoe means cooperately operate to place the tray sidewall substantially in compression during forwarding. Such a mechanism is advantageously used for forwarding filled trays between various stations, conveyors, elevator lifts and the like as are used in automatic wrapping or packaging apparatus, and with a minimum incidence of tray breakage.

United States Patent Hargash 14 1 June 13, 1972 [54] TRAY FORWARDING MECHANISM Primary Examiner-Joseph Wegbreit [72] inventor. Paul Hargash, Saginaw, Mich. Assistant Examiner Hadd S Lane [73] Assignee: The Dow Chemic l Co Midl d, Attorney-Griswold & Burdick, Burke M. Halldorson and Mich. Richard G. Waterman [22] Filed: Jan. 6, 1970 57 ABSTRACT [21] APPL N04 893 A mechanism for pushing forward filled trays such as pulp or plastic trays comprising a shoe means having a slanted face 52 us. c1 ..19s/221 imlined flushly engage the sidewall and Slightly [51 1 B658 25/08 same while forwarding such that the sidewall is lifted into press 1 1 fSe h 198 221; 271 44 sure engagement against Ofa means [5 1 Fe do arc I block disposed above the shoe means. The stop block and [56] References Cited shoe means cooperately operate to place the tray sidewall substantially in compression during forwarding. Such a UNITED STATES PATENTS mechanism is advantageously used for forwarding filled trays between various stations, conveyors, elevator lifts and the like 2,677,543 5/1954 Ohm ..271 44 as are. used in automatic mapping or packaging appmws i g g;l l g et and wlth a minimum incidence of tray breakage. 1e s 2,158,505 5/1939 Horgan ..27l/44 3 Claims, 4 Drawing Figures PATENTEuJun 13 I972 3. 669.248

INVENTOR. Pau/ Her/gash BY em 7!. W

HTTORNEY TRAY FORWARDING MECHANISM 1. Field of the Invention The present invention relates to an improved finger mechanism for pushing forward filled trays such as plastic or foam trays, by exerting force against the tray sidewall. More particularly, the invention relates to such a finger mechanism having utility for use in package wrapping apparatus of the type adapted to receive plastic or pulp trays pre-filled, for example, with ground or cut meat products, and, thereafter, to wrap the tray and product in a hermetically tight envelope of transparent film, the finger mechanism being adapted to forward the trays to and from various stations such as, for example, wrapping, sealing and labeling stations.

2. Discussion of the Prior Art Machine wrapping of packages including trays such as pulp or plastic foam trays, is frequently troubled by a high incidence of tray breakage. Plastic foam trays, for example, oftentimes weaken with age, that is, they become more brittle and therefore tend to fracture or break more easily following, for example, prolonged storage intervals. Even fresh" plastic foam trays frequently show a high incidence of breakage in that the same are usually not of uniform quality. In other words, foam trays of poorer quality such as those having thin spots or thinner than usual sidewalls, oftentimes break or fracture when handled by present-day automatic wrapping apparatus.

Perhaps the most serious tray abuse by wrapping apparatus occurs when the tray in a filled condition, is pushed forward through a tauntly draped film to effect wrapping of the film about the tray. Packaging apparatus of a type frequently employing such film wrapping techniques, for example, is illus trated in some detail in U.S. Pat. No. 3,248,848.

Undoubtedly, of course, tray manufacturing and quality control standards can be raised in order to reduce the level of tray breakage when the same are handled by automatic wrapping equipment. For example, such trays could be formed from heavier or thicker foam sheet materials. By use of the principles of the present invention, however, tray breakage is reduced if not eliminated, and without the necessity of employing heavier or stronger and more expensive tray constructions.

It is therefore among the objects of the present invention to provide the following:

A forwarding or finger mechanism capable of pushing forward filled trayssuch as plastic or foam with minimum or no incidence of tray breakage;

Such a mechanism that exerts substantially a compressive force on the tray sidewall while pushing the same forward, and with minimum application of bending force, the latter of which can frequently crack or fracture the sidewall; and

Such a mechanism adapted for ready incorporation into automatic wrapping or packaging equipment.

BRIEF SUMMARY OF THE INVENTION Briefly then, the present invention contemplates an improved forwarding mechanism for pushing forward filled trays such as those comprised of plastic foam or molded pulp, the mechanism being particularly adapted for incorporation into automatic package wrapping equipment. Such a mechanism can comprise a shoe member preferably having a slanted face inclined to flushly engage the tray sidewall. A stock block or stop means is disposed a spaced distance above the shoe. In operation, the shoe is moved against the sidewall lifting the tray slightly while pushing forward, and into pressure engagement against the underside of the stop block. The stop block and shoe means cooperatively operate to place the tray sidewall substantially in compression, with minimal or no bending forces placed thereon during forwarding or pushing forward. As will be explained more fully hereinafter, even trays of delicate or brittle sidewall construction or defect trays having sidewalls thinner than specification, are forwarded without breakage by the aforedescriibed finger mechanism.

Moreover, such a mechanism is readily incorporated into present day wrapping apparatus with only minor changes, if any, necessary.

The preferred embodiment of the present invention is shown in the accompanying drawings wherein wheresoever possible like reference numerals designate corresponding materials and parts throughout the several views thereof wherein:

FIGS. 1 and 2 are side views schematically representing the forwarding mechanism of the present invention and that of the prior art, respectively;

FIG. 3 is a front view of the mechanism of the FIG. 1; and

FIG. 4 is a view like FIG. 1 only showing a modified form of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, there is shown the forwarding or finger mechanism of the present invention as generally denoted at 10, the same including a mounting assembly 12 having upper and lower parts 14 and 16, respectively. Spacers 18 are fitted or interposed between parts 12 and 14. By fitting more or fewer spacers 18 between parts 14 and 16, a con-' venient method of adjustably lowering or raising mechanism 10 is provided, such adjustments being made simply by fastening and unfastening parts 14 and 16 and removing or adding spacers 18 to adjust to appropriate height.

Mechanism 10, in addition, includes a plurality of elbowshaped fingers or arms 20 (see FIG. 3) aligned in series, and rigidly attached at one end 22 to part 16, and which extend generally downwardly and outwardly therefrom, and then vertically downwardly at their lower end portions 26, respectively. End portions 26 each rigidly mount a first member or shoe 30 having an inclined or slanted face 32; and spaced above shoe 30, a second generally rectangularly shaped member, stop means or block 34.

Located to the right of fingers 20, is a tray 36 supported on table means 38, and filled with product 40, the latter comprising, for example, ground beef, steak, chops or the like, and normally weighing 1 to 5 pounds depending on product type and accommodating tray size.

In operation, fingers 20 are forwarded by movement of mounting assembly 12. Inclined face 32 of shoe 30 thus flushly engages the tapered sidewall 42 of the tray, slightly lifting while forwarding the same, whereby tray rim 44 is lifted into pressure engagement against the underside of stop block 34, as is shown in dotted lines in FIG. 1 denoting a forwarded posi tion of fingers 20. While not precisely understood, the force applied to sidewall 42 cooperatively by stop block 34 and shoe 30, apparently places the sidewall substantially. in compression, and with minimum or no appreciable bending forces applied to the wall.

When adapted or incorporated into an automatic wrapping apparatus of a type such as is illustrated in U.S. Pat. No. 3,248,848, mechanism 10 can be operated automatically to move reciprocally as indicated by arrows 46 and, thereby repeatedly push forward filled trays 36 from and off table me ans 38. Frequently, such wrapping apparatus requires the filled tray to be pushed through a taunt, vertically draped length of film to accomplish wrapping the film around the top and bottom sides of the tray and across its front portion. Subsequently, operations complete wrapping of the film in the form of an open-ended tube about the filled tray, and the tray is thereafter forwarded to a suitable station such that the ends of the film can be tucked and hermetically sealed.

In any event, movement of the tray through the film is accompanied by a certain degree of resistance, table means 38 adding to such resistance principally due to the appreciable weight of product 40 placed in tray 36. It is not uncommon, therefore, that several pounds or more of pushing force is required to forward tray 36 such as off table means 38 and through a draped film as explained above. Using mechanism 10, however, five and ten fold the normally required force (approximately 15 to 30 pounds) has been exerted in trials against plastic foam trays 36 without incident of tray breakage. Thus, by practice of the present invention breakage problems, especially with brittle trays or those including structural deficiencies, are substantially, if not altogether, eliminated.

Preferably, face 32 of shoe 30 is smoothly finished to present a surface having a low co-efficient of friction, and is inclined or slanted an amount approximate to the taper of sidewall 42. Face 32 can comprise, for example, stainless steel of substantially smooth surface characteristics. Optimally, the spacing X between stop block 32 and shoe 30 is in the range of about 1 A to about 4 times that of the thickness of rim 44.

A modification of the present invention is illustrated in FIG. 4 showing a stop block construction 34a slidably raiseable and lowerable on finger 20a via loosening and tightening of set screw means 48. Stop block 34a is thus conveniently movable to adjust mechanism a for application in forwarding trays 36 of variable sidewall heights.

The prior art mechanism A, as denoted in H6. 2, applies pressure principally at the top portion of the tray thereby exerting considerable bending forces to the tray sidewall. Such bending forces frequently result in breakage of the sidewall as denoted in dotted lines showing a forward position of mechanism A, and breakage of the tray at region B.

While certain representative embodiments and details have been shown for the purpose of illustrating the invention, it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention.

Accordingly, what is claimed is:

l. A device for pushing forward product filled trays or like containers of a general type including a bottom wall, and an upstanding generally upwardly and outwardly tapered sidewall, said device comprising a table means defining a generally flat horizontal surface portion to receive and support the bottom wall of the container, a plurality of side by side, laterally spaced apart fingers, said fingers each including a pushing face positioned to engage the sidewall of said container, means to reversely move said fingers as a unit along a linear path traversing at least a part of said table means, said pushing faces being configured to generally flushly engage said sidewall and to slide said sidewall upwardly thereon away from said table means responsive to engagement therewith and forward movement of said fingers, and means to engage the top edge portion of said sidewall to restrain the same against the upward bias given thereto by said pushing faces accompanying forward movement of said fingers.

2. The device of claim 1 wherein said restraining means comprises an underside surface facing generally downwardly toward the plane of said table means.

3. The device of claim 2 wherein said underside surface overhangs at least a part of said pushing faces. 

1. A device for pushing forward product filled trays or like containers of a general type including a bottom wall, and an upstanding generally upwardly and outwardly tapered sidewall, said device comprising a table means defining a generally flat horizontal surface portion to receive and support the bottom wall of the container, a plurality of side by side, laterally spaced apart fingers, said fingers each including a pushing face positioned to engage the sidewall of said container, means to reversely move said fingers as a unit along a linear path traversing at least a part of said table means, said pushing faces being configured to generally flushly engage said sidewall and to slide said sidewall upwardly thereon away from said table means responsive to engagement therewith and forward movement of said fingers, and means to engage the top edge portion of said sidewall to restrain the same against the upward bias given thereto by said pushing faces accompanyIng forward movement of said fingers.
 2. The device of claim 1 wherein said restraining means comprises an underside surface facing generally downwardly toward the plane of said table means.
 3. The device of claim 2 wherein said underside surface overhangs at least a part of said pushing faces. 